In any communications structure for cellular telephony, it is well known how a set of base station are used to communicate by radio with the mobile terminals that form part of the system, these stations being connected to a base station controller which manages their operation.
This is explained in the article "Sistemas de Movilidad Local" by L. Martinez, published in the Revista Espanola de ElectroL. Martinez, published in the Revista Espanola de Electronica, May 1993, pages 34-39.
In this publication various architectures are shown for cordless subscriber loops consisting of mobile terminals, base stations and various types of switches that perform the function of base station controller, for example the cordless private branch exchange of FIG. 6, page 37, which, in addition to being connected to base stations, also permits connection with standard and extended service telephone sets.
The connections between the private branch exchange and the base stations are made, as indicated on page 39 of the article mentioned, by means of twisted wire pairs over which data are transmitted at 2048 kb/s (CCITT Recommendation G-702).
Under these circumstances, although not stated in the article mentioned, there is a clear need for an interface conversion which implies the availability of associated subsystems for clock generation, temporary storage memories in which the read/write processes for transmission frequency conversion take place, which, in turn, produces a small delay that has to be taken into account, etc. As a result, the complexity of the equipment, its cost, and the delays produced in interface conversions that are made in the communications process between the private branch exchanges and the base stations increase considerably.